1. Field of the Invention
This invention relates to a rotary expansible chamber device useful for the compression and/or expansion of compressible fluids. More particularly, this invention relates to a rotary expansible chamber device useful as a compressor, wherein a compressible fluid is compressed within the device, or as a fluid motor, wherein a compressed fluid is expanded and converted into mechanical energy.
2. Description of the Prior Art
Rotary prior art devices useful for either compressor or fluid motor functions have traditionally consisted of either a screw type compressor or Roots-type blower. Generally, if compression is to occur within the device itself, both types have required either timed inlet and outlet ports or transverse gas flow.
U.S. Pat. Nos. 3,941,521; 4,033,708; 4,076,469 and 4,437,818 are drawn to Roots-type compressors with "precompression" taking place within the working chambers. To accomplish the precompression feature the devices function such that the impellers are open to intake air along the entire axial length thereof and precompression takes place by the rotating of the impellers until the impellers reach a point where further rotation thereof causes a valving action of the gases through a port in the wall of the housing. This compression is theoretically adiabatic. However, once the precompression air in the impellers becomes freely communicating with the outlet port in the housing wall further rotation of the impellers constitutes a nonadiabatic compression at a constant pressure. The flow path in these devices is essentially transverse to the axial plane of the impellers and it is taught that limiting the axial length of the impellers to the minimum number of profiles or risers on each impeller prevents costly axial leakage and improves the efficiency of the compressor.
Screw compressors which provide for sealed axial flow of a compressible gas are shown in U.S. Pat. Nos. 1,735,477 and 2,652,192. These screw-type compressors exhibit good theoretical adiabatic compression efficiency; however, because of the high number of knife edge seals and the three dimensional construction required they are considered to be high leakage devices and are complicated and expensive to manufacture.
While the above devices have been considered as compressors they could function as fluid motors by reversing the fluid flow through them but would have the same disadvantages.
In none of the above cited patents is there taught an efficient compressor or fluid motor consisting of intermeshing, impellers which are capable of adiabatic compression or expansion of compressible gases by means of axial flow of sealed volumes therethrough.
Additional patents considered which have one or more parts somewhat similar in design or function to one or more parts of the invention to be described are found in U.S. Pat. Nos. 158,277; 3,865,524 and 3,938,915.